Stop-motion mechanism for sewing machines

ABSTRACT

Improved mechanism for controlling the operation of a groupstitch sewing machine and for stopping the machine at the end of a cyclical operation at such a time in the revolution of its main drive shaft as to position the needle of the machine out of engagement with the work so as to enable ready removal of a stitched workpiece and the introduction of a new workpiece. The stop-motion mechanism for the sewing machine is of a character which enables operation of the machine at a high speed in producing a group of stitches. Shock absorbing means are provided for absorbing the impact on the driven mechanism of the machine when a positive stop motion is imparted to the machine. A special motor enables driving of the machine at two different speeds, so that in the normal course of operation the machine is driven at speeds above 3,000 r.p.m., but when the machine is to be stopped the motor is converted to a slower speed, for example one-half the normal speed of operation. Power assist means, in the form of pneumatically operated devices, are provided for assisting in the performance of certain operations, such as raising work clamping means and operating a cycle starting mechanism.

United States Patent 1,422,639 2,721,526 10/1955 lvanko 2,822,771 3,245,369

STOP MOTION MECHANISM FOR SEWING MACHINES 14 Claims, 8 Drawing Figs.

U.S. Cl. 112/67 Int. Cl D05b 69/20 Field of Search 1l 2/67,

65, 219,219 (A), 219 (F.O.), 220, 87

References Cited UNITED STATES PATENTS 7/1922 Valois Inventors Appl. No. Filed Patented Assignee 2/1958 HaleetaL. 4/1966 Myska Primary ExaminerH. Hampton Hunter Att0rney H. C. Dieserud ABSTRACT: Improved mechanism for controlling the operation of a group-stitch sewing machine and for stopping the machine at the end of a cyclical operation at such a time in the revolution of its main drive shaft as to position the needle of the machine out of engagement with the work so as to enable ready removal of a stitched workpiece and the introduction of a new workpiece. The stop motion mechanism for the sewing machine is of a character which enables operation of the machine at a high speed in producing a group of stitches. Shock absorbing means are provided for absorbing the impact on the driven mechanism of the machine when a positive stop motion is imparted to the machine. A special motor enables driving of the machine at two different speeds, so that in the normal course of operation the machine is driven at speeds above 3,000 rpm, but when the machine is to be stopped the motor is converted to a slower speed, for example one-half the normal speed of operation. Power assist means, in the form of pneumatically operated devices, are provided for assisting in the performance of certain operations, such as raising work clamping means and operating a cycle starting mechanism.

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35 I &; STARTING CYLINDER r-34'b I FEED CLAMP 1L|FTING .CYLINDIER 33 TWO SPEED 74 MOTOR TO STARTING CYLINDER 34- To FEED CLAMP r LIFTING' 33 CYLINDER STOP MOTION MECHANISM FOR SEWING MACHINES This invention relates to improved control'mechanism for sewing machines adapted for cyclical operation to produce a predetermined group of stitches.

An object of the invention has been to enable the operation of such group-stitch sewing machines at higher speeds than has been possible heretofore. Such cyclically operated sewing machines have been limited to operations at speeds of not more than 2,000 rpm. in order to prevent damaging of the machine upon its suddenly stopping at the end of each cycle, with the stitch forming mechanism at a particular stage in its operation so as to facilitate the removal of completed workpieces and the introduction of new workpieces.

Towards the foregoing end the present invention involves an improved form of shock absorbing means which serves to minimize any detrimental effect on the mechanism of the machine as it is brought to a stop. The improved shock absorbing means serves to effectively cushion the final stop impact. It comprises a vertically disposed, rockable frame having its upper portion surrounding the main drive shaft of the machine. A stop bushing is journaled within the top portion of the frame and this bushing surround the main drive shaft with a slight clearance in relation thereto. A portion of the bushing has a downwardly extending arm which is connected with a plunger rod that extends downwardly in alignment with the axis of the drive shaft-The plunger rod is urged downwardly by a spring, and the arrangement is such that when the machine is to be brought to a stop upon the completion of a predetermined number of stitches the downwardly extending arm of the bushing will be urged into cooperation with a stop notch provided in a hub portion of one member of a two-part pulley through which the machine is driven by a belt extending from a driving motor. This particular stop mechanism has been found to be exceptionally desirable in absorbing the im pact of the positive stop applied to the machine.

A further feature of the invention is the employment of a special type of two-speed motor which normally drives the machine at speeds above 3000 rpm. but is brought down to a much lower speed electrically before braking devices are brought into action to stop the machine with the needle in a position in which it is fully disengaged from the work. The motor employed is preferably a three-phase, multispeed squirrel-cage motor, to which power is supplied from a 220-volt 60- cycle source. The connection between the motor, which is wound for two speeds, and the power source includes an electromechanically operated series of switches for shifting the connections from the power source to the input terminals of the motor in a manner to change the operation of the latter from one speed to another. A multiple pole relay involved in the connection under discussion is preferably connected into a l l-volt 60-cycle source of alternating current. It is energized by the closing of a switch by an element mounted on a pattern cam that is driven at a suitable speed by connections from the main drive shaft of the sewing machine. The arrangement is such that the switch closing element is brought into engagement with the switch after a predetermined number of stitch forming operations have been nearly completed, i.e. the number of revolutionsof the main drive shaft of the machine required for the production of a group of stitches is about to be completed.

A further feature of the present invention is the provision of pneumatic devices as power assist means for bringing about the raising of a work engaging clamp upon completion of a cycle of operations and also for operating the cycle-starting mechanism. It has been found that the manual energy required to perform these functions by hand or knee press or foot pedal means is excessive, and when the operator becomes tired they may not be properly carried out.

With the foregoing objects, features and advantages of the invention in view, an illustrative embodiment of the same will now be described in further detail in connection with the accompanying drawings of which:

FIG. 1 is a view partly in elevation and partly in vertical section showing the means for controlling the operation of a sewing machine of the character mentioned;

FIG. 2 is an end elevational view of the machine as seen from the right in FIG. 1;

FIG. 3 is a partial elevational view and partial vertical sectional view of the machine as seen from the opposite side from that of FIG. 1;

FIG. 4 is a detailed view partly in vertical section and partly in elevation through an upper portion of the machine in a plane along the line 4-4 of FIG. 1;

FIG. 5 is a bottom view of machine showing a pattern cam in detail;

FIG. 6 is a schematic view showing certain control valves and power assist means provided in accordance with the invention;

FIG. 7 is a schematic view showing the circuitry involved in controlling the operation of the two-speed motor; and

FIG. 8 is a schematic view of a treadle that may be incorporated in the system for the control by the operator of the commencement of a cycle of operation of the machine.

The invention as disclosed in the drawings has been shown as applied to sewing machines of the type disclosed in the Ivanko US. Pat. No. 2,721,526 granted Oct. 25, 1955; in the US. Pat. to Hale et al. No. 2,822,771, granted Feb. 11, 1958, and in the US Pat. to Ketterer et al. No. 2,906,222, granted Sept. 29, 1959. Reference may be made to those patents for certain details of the construction. The present specification is, accordingly, directed primarily to those aspects of the machine which are considered to be improvements over the constructions of machines embodying stop-motion mechanism adapted to automatically stop the machine at the end of a group-stitching operation, with the main drive shaft in a selected position as explained above.

Referring now to the drawings the machine has a base portion 10 the top 11 of which is adapted to be positioned within an opening in a work-supporting table. From the base portion there rises a vertical standard 12 having a work-supporting arm 13 extending laterally therefrom at an intermediate point along the vertical standard, and having a laterally extending arm 14 at the top of the vertical standard. It will be understood that this upper, laterally extending arm is provided at its outer end with a head portion, not shown, but which may be of the general character disclosed in the Ivanko and I-Iale et al. patents mentioned. A main drive shaft 15 of the machine extends longitudinally of the upper arm 14 and extends outwardly from the vertical standard, as shown toward the right in FIG. 1, to enable it to be connected with a driving source by means of a belt receiving pulley 16. As disclosed in the abovementioned patents this pulley has two components 16a and 16b, the component 16 a being secured to the shaft for imparting rotation thereto and the portion 16b being mounted for free rotation in relation to the shaft when the machine is at rest. A belt 17, preferably of partially V-shaped cross section, is trained around the upper portion of the pulley, and when the machine is at rest it is adapted to move freely in relation to the part 16a of the pulley but may serve to turn the loose part 16b of the pulley. Conventional means, such as an arm 18 carried by a rod 19 extending laterally from a rockable frame 20, may be provided with a pivoted element 18a for engaging a thrust bearing member within a housing 21, extending outwardly from the part 16b of the pulley in alignment with the drive shaft, to urge the part 16b against the belt and the latter against the part 16a, thus bringing about the driving of the shaft 15. In accordance with the present invention, the rocking of the frame 20 about its pivot 20a is accomplished through the manual control of pneumatically operated means, by connectionsfrom a foot treadle or the like, to bring about the starting of a cycle of operations of the machine. Such manual control may, for example, be performed by connections from a foot treadle 22, as shown in FIG. 8. The treadle is normally urged into the position shown in FIG. 8 by a spring 22a. In this position an engagement member 22b is in contact with a plunger 23a of a four-way valve 23, which is arranged to receive air under pressure from a suitable source through a line 24, FIG. 6, and a unit 25, which is a flter-lubricator-regulator for controlling the proper operation of the system. From this unit the air is passed to the four-way valve 23 through a line 26.

As shown schematically in FIG. 6, the air delivered through the line 26 is directed along the path of the full-line arrow to a line 27 which delivers the air under pressure to a valve 28. This is normally closed, but it is adapted to be opened for the delivery of the air through a line 29 to a feed clamp lifting cylinder 30. As will be explained, this occurs upon the completion of a cycle of operations of the machine and the automatic stopping of the machine with the main drive shaft thereof in a particular position. It is at this time that the rockable frame mentioned above will be shifted toward the right in FIG. 1 to bring about the stopping of the machine with its main shaft in the desired position. Such rocking of the frame 20 will cause a stud 20d carried thereby to be urged against a roller carried by an arm 28b, and this will in turn engage a plunger 28a of the valve 28. This will open the valve 28 and deliver the air through the line 29 to the cylinder 30 at the right end thereof (FIG. 6) thereby causing its piston to draw toward the left a piston rod 30a which is connected by a cable 30b with a lever 32. The downward movement of the outer end of this, as viewed in FIG. 2, which is the right end as shown in FIG. 6, will impart a lifting movement to the work clamping means 31, FIG. 6, which may be of the character shown in the Hale et al. patent mentioned above, and in the US. Pat. to Graham et al. No. 2,990,795, granted July 4, 1961, thereby enabling the ready removal of a workpiece and the introduction of another workpiece to be stitched. The connections from lever 32 to the clamping means 31, as shown schematically in FIG. 6, includes a link 310 connected with a rock arm 31b secured to a rock shaft 310, the opposite end of which carries a rock arm 310' connected by a link 3le with a member 31 f secured to a clamp opening bar 31g which is normally spring urged downwardly. At the lower end of bar 31g there is secured an engagement block 31h adapted to engage a pin 31k carried by the clamp jaw 31.

When the new work piece has been introduced into the stitching zone, the foot treadle 22 is depressed slightly to carry the contact element 22b into a region intermediate the two plungers 23a and 23b of the valve 23. This brings about the discharge of air from the feed clamp lifting cylinder 30 through lines 29 and 27 to the valve 23 and enables the discharge of the air through an outlet 23d. At this time the work clamp is lowered. Then upon further depression of the foot treadle, the contact element 22b will be engaged with the plunger 23!) of the valve 23 and thus bring about delivery of air from the source 24 to and through the valve 23, and along the broken line 23c shown in FIG. 6 into a line 33 which delivers the air to the starting cylinder 34. The piston rod 340 extending from the piston of this cylinder is connected by a cable 34b with a lever 35. This lever is pivotally mounted on the pin 20a and has its left end (FIG. 1) suitably connected, as by means of the character shown in the Ketterer et al. patent mentioned'herein, including a vertical rod 35b, with a latch lever 36 (FIG. I). The latter is connected by a link 37 with the member 20 and serves to disengage the stop motion mechanism described above, when the lever 36 is rocked in a counterclockwise direction into the position shown in FIG. 1. Also it brings about the operation of the arm 18 to urge the section 16b of the pulley against the belt 17, and to urge the latter against the cooperating surface of section 160 of the pulley, so that a new cycle of operations will be commenced.

In connection with the foregoing it is to be noted that FIG. 1 discloses the pulley member of the machine in an operative condition so that the machine is then in operation. The latch lever 36 is held in the position indicated by a spring-urged pawl 38. It will be understood that when a particular cycle of operation is completed, the latch lever 36 will be released to rock in a clockwise direction into a position in which the member 20 and related parts are shifted toward the right in FIG. I to bring about the stopping of the machine. Such release is effected by a link 39 connected at one end with the pawl 38 and at the other end with a pattern can following means of the character disclosed in the Ketterer et al. patent mentioned hereinabove.

The pattern cam which controls the operation of the machine in a cycle of stitch-forming operations is shown at 40 in FIGS. 1, 2, 3 and 5. It is mounted for rotation in a base portion of the frame of the machine. Secured to the top surface of the pattern cam is a gear 41 which meshes with a pinion 42 secured to the lower end of a shaft 43 (FIG. 1). This shaft has secured to its upper end a worm wheel 44 which meshes with a worm 45 secured to the main drive shaft 15 of the machine. The arrangement is such that the pattern cam 40 will be given one revolution for a plurality of revolutions of the main drive shaft. This enables the formation of a desired number or group of stitches in the work being handled by the machine during each cycle of operation of the machine.

It will be understood that the main drive shaft 15 of the machine is driven by the pulley I6 whenever the latter is placed in an operative condition by the swinging of the frame member 20, with its associated parts, into the position shown in FIG. 1. When the machine is to be stopped, upon the completion of a group of stitches, the member 20 willbe swung toward the right about its pivot 20a under the action of springs 20b and 200. The mechanism for stopping the rotation of the main shaft 15 upon the completion of the group of stitches involves a stop bushing 46 which has some freedom of movement within the upper portion of the member 20 due to the clearance shown in FIG. 4. The bushing has an enlarged head portion 460 to the right of the frame member 20, FIG. I, and it has a downwardly extending arm 46b. The latter has pivotally connected with its lower end the flattened upper end of a plunger rod 47. This rod extends through an opening in a bearing stud 20d which has a reduced diameter portion 20e extending through the frame 20. A screw 20f retains the bearing stud on the frame, but in a manner permitting some turning of the stud in relation to the frame in the course of a stopmotion operation. The plunger rod 47 extends through a normally vertically disposed opening in the stud 20d, and it has a coil spring 48 surrounding it, with'the upper end of said spring engaged with a flattened bottom provided on the stud 20d and its lower end engaged with a nut 49 having screw threaded engagement with the lowerend of the plunger rod. The nut 49 may be adjusted to provide the desired amount of compression force in the spring 48 to be exerted on the plunger rod and a lock nut 50 may be then turned into position to retain the parts as adjusted. The upwardly extending portion of the plunger rod 47 is surrounded by a compression spring 51, the upper end of which abuts against the bottom of the flattened upper end of the plunger rod, while the lower end of the spring 51 urges a felt washer 51a downwardly against the top of the bearing stud 20d. This enables the retention of lubricant in the region of relative movement of the plunger rod in relation to the stud.

In the normal operation of the machine the plunger rod will apply a certain downward force to the bushing 46, to urge it against the supporting surfaces of the frame 20. However it is not urged against the main drive shaft, so that this may rotate quite freely within the bushing. But when the machine is to be brought to a quick stop, the right-hand surface of the bushing will be urged against the left-hand surface of a hub 16c extending toward the left from the fixed member 16a of the pulley I6. This hub is provided with an opening 164' which is adapted to receive the portion 46b of the stop bushing. This is of course when the pawl 38 releases the member 36 and permits the springs 20b and 200 to rock the frame 20 toward the right in FIG. I. The right-hand surface of the enlarged portion 460 of the bushing will be urged into engagement with the lefthand surface of the hub 16c, which is of helical form and slopes at a slight angle to a plane perpendicular to the axis of the hub. When the opening 16d of the latter is brought to its lowermost position, the downwardly extending portion 46b of the bushing 46 will enter the opening and bring about a quick stopping of the main drive shafl. A certain amount of turning of the shaft will continue, with the result that the arm 46b of the bushing will be swung through a certain angle and will draw the plunger rod 47 upwardly against the force of the spring 48.

To assist in bringing the drive shaft of the sewing machine to a quick stop in the manner explained above, there is also-provided a brakeshoe arrangement adapted to cooperate with the face of the fixed member 16a of the pulley 16. This brakeshoe involves a substantially vertically disposed lever 52, FIGS. '3 and 4, which is pivotally connected with the frame by means of a bolt 53. The upper portion 52aof the lever 52 is disposed at an angle to the vertical, as best shown in FIG. 4. To this there is secured an arcuate brakeshoe 54. On the pulley engagement side, the brakeshoe is provided with a layer 55 of a high friction material such as leather or the like. This layer is forced against the adjacent side of the fixed pulley member 16a during the stopping of the machine. To vary the force with which the brakeshoe is urged against the pulley, in the manner explained, there is provided on the upper portion 52a of the lever 52 an adjusting stud 56. This as best shown in FIG. 3 has a collar 56a intermediate its ends, and with this cooperates a spring 57. The latter has its left end engaged with the righthand surface of collar 56a and has its right end in engagement with a surface on the frame of the machine. By appropriateadjustment of the stud 56, the amount of force with which the brakeshoe is urged against the fixed member 16a of the pulley may be varied to produce the desired amount of braking action. A split clamp 58 serves to retain the stud 56 in the desired position. Also for controlling the magnitude of engagement of the brake shoe against the pulley, there is provided an eccentric stud 59. This is received in a suitable bore in a bearing lug extending through the lever 52 at substantially the midpointof the latter. The free end 59a of the stud 59 is eccentric in relation to the main body of the stud so that rotation of the latter serves to adjust the position of said free end relative to the upper portion of the frame 20. Accordingly the turning of the stud 59 on the lever 52 will serve to vary the magnitude of the maximum engagement of the brakeshoe with the surface of the fixed member 16a of the pulley. Also the adjustment of the stud 59 will serve to time the engagement of the brakeshoe with the surface of the pulley. I

As has been previously indicated, the preferred embodiment of the present invention involves the use of a two-speed squirreheage motor. Referring to FIG. 7 it is shown schemati cally at 64 and is of the two-winding type. It receives current from a three-phase 220-volt 60-cycle source of electric power indicated at 65. Throughout the major portion of the operation of the sewing machine the current from source 65 will pass through a three-arm switch with the current flowing from contacts 73 to contacts 74. However, when a particular stitching cycle, involving a desired number of stitches, is approaching completion, a relay 70 will have its coil 71 energized to swing the switch arms 73 away from contacts 74 and into engagement with contacts 75. Energization of the coil 71 is brought about under the control of the pattern cam 40 which has an engagement member 62 (P10. 5) secured thereto in the desired position for cooperation with a switch 61. The latter is connected into a Itovolt -cycle electric current source 63, which may come from one of the leads of source 65, and when closed will deliver this current to the coil 71 of relay 70. Through activation of the relay with the resulting switching of the arms 73 from contacts 74 to contacts 75, there will result a reduction in the speed of the motor to onehalf the speed which it has had during the major portion of the stitching operation. This naturally provides a braking action which will slow down the operation of the main drive shaft of the machine to one-half the speed whichit has had in performing the group stitching operation. As a result of this, the other aspects of the stop-motion means for the main shaft of the machine will be carried out quickly and with a minimum of impact. 1

If desired, the two-speed motor 64'may' be of the one-winding type which is provided with a Dahlander connection and is known as a consequent-poled motor. In this event, the energization of a relay similar to that shown at 70 will bring about a reduction in the speed of the motor to one-half of its normal speed in a well-known manner.

It will be understood, in connection with the foregoing, that the pattern cam 40 will, at the time indicated, also bring about the engagement of the brakeshoe, with the portion of the pulley and will simultaneously operate the pawl 38 to bring about the decoupling of the two sections of the pulley. This completely removes the driving power of the V-belt from the motor to the drive shaft of the sewing machine. By the time this decoupling action has been completed, the engagement member 62 on the pattern cam will have moved beyond the switch 61 so that the relay 70 will be deactivated and the motor 64 will resume its high-speed operation in readiness for another group stitch operation.

An important advantage of having the stop motion bushing provided with a downwardly extending arm adapted to cooperate with the notch in the hub of the flange of the pulley that is secured to the drive shaft, rather than having said arm extending horizontally from said bushing as disclosed in the Hale et al. patent, is that it permits the shaft to rotate more than 90 before it is positively stopped. By the novel arrangement here being claimed, the shaft may rotate an arcuate distance approaching after the bushing has been engaged. This enables the drive shaft to be rotated at much higher speeds; i.e., as high as 3,000 r.p.m., and still have it come to a stop in a desired position in which the needle is well above the work.

While an illustrative embodiment of the invention has been described and shown in some detail, it will be understood that various changes may be made in certain details of the construction within the scope of the invention, as defined by the appended claims.

We claim:

l. Group-stitch sewing apparatus including a sewing machine having a main drive shaft, said apparatus being adapted for the automatic formation of a group of stitches successively on workpieces fed to the machine, a stop-motion mechanism for stopping the machine with its drive shaft in a predetermined position of rotation, which comprises a clutchtype pulley having two flange portions, one of said flange portions being secured to the drive shaft of the machine for rotation therewith, the other of said portions being mounted for free rotation relative to the drive shaft, a V-belt surrounding said pulley and extending from a motor which drives said belt, a rock member pivotally connected with the frame of the sewing machine and provided with a bushing. adjacent its upper end which surrounds the drive shaft, said bushing having a downwardly extending arm lying in a vertical plane in alignment with the axis of said shaft, said flange portion of said pulley which is fixedly mounted on said shaft having a hub portion extending toward said bushing, said hub portion having a notch therein adapted to receive the downwardly extending arm of said bushing, spring means adapted to rock said member about its pivotal connection with said frame to carry said bushing into contact with said hub portion of said flange of the pulley, means under manual control for initiating the operation of the drive shaft of the machine by urging said flange portions of the pulley into active engagement with said V-belt, spring means connected with said downwardly extending arm of the bushing and lying in the above-mentioned vertical plane, said spring means being adapted to resist turning movement of said bushing, thereby imparting aresilient stopping action to the rotation of the pulley portion secured to the main drive shaft of the machine when said arm of the bushing enters the notch in said hub portion.

2. Group-stitch sewing apparatus as set forth in claim 1 in which means are provided for retaining said means under manual control in its activated position to continue the operation of the drive shaft of the machine, and means for automatically releasing said manual control means upon the completion of a group of stitches.

3. Group-stitch sewing apparatus as set forth in claim 2 in which a pattern cam is mounted for rotation on the frame of rite machine, connections from the drive shaft of the machine for rotating said pattern cam and means controlled by said pattern cam for releasing said means under manual control.

4. Group-stitch sewing apparatus as set forth in claim 1 in which a pattern cam is mounted in association with said sewing machine, connections from said drive shaft for rotating said pattern cam at such an angular rate that during a single revolution of the cam the main drive shaft of the machine will have caused completion of the desired group of stitches, a switch carried by the frame of the sewing machine, means carried by said pattern cam for closing said switch, a relay energized upon the closing of said switch, and means operated by said relay for reducing the speed of operation of said motor.

5. Group-stitch sewing apparatus as set forth in claim 1 in which the frame of the sewing machine has a subbase portion, a pattern cam rotatably mounted in said subbase portion, connections from said main drive shaft of the machine for rotating said pattern cam, a switch carried by said sub base portion, means carried by said pattern cam for closing said switch toward the end of the completion of a group of stitches, and means controlled by said switch for substantially reducing the speed of operation of said motor.

6. Group-stitch sewing apparatus as set forth in claim 4 in which said motor is a multispeed squirrel-cage motor, means for delivering current from a three-phase source to said motor, said means operated by said relay for reducing the speed of operation of the motor comprising a multiple pole construc- LlOl'l which changes the connections from the three-phase lines to the motor.

7. Group-stitch sewing apparatus as set forth in claim 1 in which said means under manual control for initiating the operation of the drive shaft of the sewing machine comprises a fluid operated cylinder and piston unit, manually operable means for controlling the delivery of fluid to said cylinder to shifi the piston therein, and connections from said piston for shifiing said flange portions of said pulley into active engagement with said V-belt.

8. Group-stitch sewing apparatus as set forth in claim 7 in which means are provided for withdrawing the fluid from said cylinder as the sewing machine nears completion of a group of stitches.

9. Group-stitch sewing apparatus as set forth in claim 8 in which a brakeshoe is provided adjacent the flange portion of the pulley which is secured to the drive shafi of the sewing machine, and means for urging said brakeshoe against said flange portion of the pulley upon completion of said group of stitches.

l0. Group-stitch sewing apparatus as set forth in claim 1 in which said spring means connected with said downwardly extending arm of the bushing comprises a rod surrounded by a coil spring, said rod being normally disposed vertically with its axis perpendicular to the axis of said drive shaft.

11. Group-stitch sewing apparatus as set forth in claim l0 in which the axis of said rod is disposed in parallel relation to said rock member, a stud pivotally connected with said rock member with its axis perpendicular to the latter, said rod having a sliding movement in relation to an opening through said stud, said coil spring having one end thereof in engagement with said stud, and adjustable means carried by said rod cooperating with the other end of said spring.

12. Group-stitch sewing apparatus as set forth in claim 11 including motor-controlling means for substantially reducing the driving speed of said motor by changing the delivery of current thereto and thus imparting a braking action to the momentum of the machine.

13. Group-stitch sewing apparatus as set forth in claim 12 in which said motor is a three-phase multispeed squirrel-cage motor, and said motor-controlling means including a relaycontrolled switch connection.

14. Group-stitch sewing apparatus as set forth in claim 1 in which means is provided for supporting the work to be stitched, feed clamp means for engaging the work and feeding it along the work supporting surface, a fluid operated cylinder and piston unit, connections from the piston to said feed clamp means for lifting the same from the work, and automatic means for controlling the delivery of fluid to said cylinder to cause lifting of said feed clamp upon completion of a stitch-forming cycle. 

1. Group-stitch sewing apparatus including a sewing machine having a main drive shaft, said apparatus being adapted for the automatic formation of a group of stitches successively on workpieces fed to the machine, a stop-motion mechanism for stopping the machine with its drive shaft in a predetermined position of rotation, which comprises a clutch-type pulley having two flange portions, one of said flange portions being secured to the drive shaft of the machine for rotation therewith, the other of said portions being mounted for free rotation relative to the drive shaft, a V-belt surrounding said pulley and extending from a motor which drives said belt, a rock member pivotally connected with the frame of the sewing machine and provided with a bushing adjacent its upper end which surrounds the drive shaft, said bushing having a downwardly extending arm lying in a vertical plane in alignment with the axis of said shaft, said flange portion of said pulley which is fixedly mounted on said shaft having a hub portion extending toward said bushing, said hub portion having a notch therein adapted to receive the downwardly extending arm of said bushing, spring means adapted to rock said member about its pivotal connection with said frame to carry said bushing into contact with said hub portion of said flange of the pulley, means under manual control for initiating the operation of the drive shaft of the machine by urging said flange portions of the pulley into active engagement with said V-belt, spring means connected with said downwardly extending arm of the bushing and lying in the above-mentioned vertical plane, said spring means being adapted to resist turning movement of said bushing, thereby imparting a resilient stopping action to the rotation of the pulley portion secured to the main drive shaft of the machine when said arm of the bushing enters the notch in said hub portion.
 2. Group-stitch sewing apparatus as set forth in claim 1 in which means are provided for retaining said means under manual control in its activated position to continue the operation of the drive shaft of thE machine, and means for automatically releasing said manual control means upon the completion of a group of stitches.
 3. Group-stitch sewing apparatus as set forth in claim 2 in which a pattern cam is mounted for rotation on the frame of the machine, connections from the drive shaft of the machine for rotating said pattern cam and means controlled by said pattern cam for releasing said means under manual control.
 4. Group-stitch sewing apparatus as set forth in claim 1 in which a pattern cam is mounted in association with said sewing machine, connections from said drive shaft for rotating said pattern cam at such an angular rate that during a single revolution of the cam the main drive shaft of the machine will have caused completion of the desired group of stitches, a switch carried by the frame of the sewing machine, means carried by said pattern cam for closing said switch, a relay energized upon the closing of said switch, and means operated by said relay for reducing the speed of operation of said motor.
 5. Group-stitch sewing apparatus as set forth in claim 1 in which the frame of the sewing machine has a subbase portion, a pattern cam rotatably mounted in said subbase portion, connections from said main drive shaft of the machine for rotating said pattern cam, a switch carried by said sub base portion, means carried by said pattern cam for closing said switch toward the end of the completion of a group of stitches, and means controlled by said switch for substantially reducing the speed of operation of said motor.
 6. Group-stitch sewing apparatus as set forth in claim 4 in which said motor is a multispeed squirrel-cage motor, means for delivering current from a three-phase source to said motor, said means operated by said relay for reducing the speed of operation of the motor comprising a multiple pole construction which changes the connections from the three-phase lines to the motor.
 7. Group-stitch sewing apparatus as set forth in claim 1 in which said means under manual control for initiating the operation of the drive shaft of the sewing machine comprises a fluid operated cylinder and piston unit, manually operable means for controlling the delivery of fluid to said cylinder to shift the piston therein, and connections from said piston for shifting said flange portions of said pulley into active engagement with said V-belt.
 8. Group-stitch sewing apparatus as set forth in claim 7 in which means are provided for withdrawing the fluid from said cylinder as the sewing machine nears completion of a group of stitches.
 9. Group-stitch sewing apparatus as set forth in claim 8 in which a brakeshoe is provided adjacent the flange portion of the pulley which is secured to the drive shaft of the sewing machine, and means for urging said brakeshoe against said flange portion of the pulley upon completion of said group of stitches.
 10. Group-stitch sewing apparatus as set forth in claim 1 in which said spring means connected with said downwardly extending arm of the bushing comprises a rod surrounded by a coil spring, said rod being normally disposed vertically with its axis perpendicular to the axis of said drive shaft.
 11. Group-stitch sewing apparatus as set forth in claim 10 in which the axis of said rod is disposed in parallel relation to said rock member, a stud pivotally connected with said rock member with its axis perpendicular to the latter, said rod having a sliding movement in relation to an opening through said stud, said coil spring having one end thereof in engagement with said stud, and adjustable means carried by said rod cooperating with the other end of said spring.
 12. Group-stitch sewing apparatus as set forth in claim 11 including motor-controlling means for substantially reducing the driving speed of said motor by changing the delivery of current thereto and thus imparting a braking action to the momentum of the machine.
 13. Group-stitch sewing apparatus as set forth in claim 12 in which said motor is a three-phase multispeed squirrel-cage motor, and said motor-controlling means including a relay-controlled switch connection.
 14. Group-stitch sewing apparatus as set forth in claim 1 in which means is provided for supporting the work to be stitched, feed clamp means for engaging the work and feeding it along the work supporting surface, a fluid operated cylinder and piston unit, connections from the piston to said feed clamp means for lifting the same from the work, and automatic means for controlling the delivery of fluid to said cylinder to cause lifting of said feed clamp upon completion of a stitch-forming cycle. 